If you can get a donor motor of the same year & HP its not a real hard job, I have found its easier to replace the whole transom bracket and tiller as an assembly. Not near as hard as it sounds.
Actually, you haven't given us any information. What year is the motor? Did it come from the factory as electric start, or was it added as a kit? These things make a big difference in the answer. It can be simple bolt-on job, or it can require replacing major parts.
